The conventional treatment of periodontal disease does not solve the high incidence of recolonization of periodontal pockets by pathogens. Here, we introduce an innovative concept of incorporating autochthonous bacteria as potential probiotics into nanofibers for local treatment. We selected and isolated the strain 25.2.M from the oral microbiota of healthy volunteers. It was identified as Bacillus sp. based on 16S rRNA sequence analyses. The strain is nonpathogenic, produces antimicrobial substances, and can grow over the periodontal pathogen Aggregatibacter actinomycetemcomitans in vitro, making it a promising probiotic candidate. The strain 25.2.M was successfully incorporated into the nanofibers in the form of spores (107 CFU/mg), the viabilities of which were exceptional (max. change of 1 log unit) both during electrospinning and after 12 months of storage. The release of the bacteria was delayed from chitosan/poly(ethylene oxide) compared to poly(ethylene oxide) nanofibers, and the antimicrobial activity against A. actinomycetemcomitans was confirmed. The developed nanodelivery system for administration into periodontal pockets thus offers a promising approach for the inhibition of periodontal pathogens and restoration of healthy oral microbiota.
COBISS.SI-ID: 4619633
During material treatment in dentistry particles of different size are released in the air. In order to examine the degree of particle exposure, air scanning to dental employees was performed by the Scanning Mobility Particle Sizer. The size, shape and chemical composition of particles collected with a low-pressure impactor were determined by scanning electronic microscopy and x-ray dispersive analysis. The average concentrations of nanoparticles during working periods in a clean dental laboratory (45000 to 56000 particles/cm3), in an unclean dental laboratory (28000 to 74000 particles/cm3), and in a dental office (21000 to 50000 particles/cm3), were significantly higher compared to average concentrations during nonworking periods in the clean dental laboratory (11000 to 24000 particles/cm3), unclean laboratory (14000 to 40000 particles/cm3), and dental office (13000 to 26000 particles/cm3). Peak concentration of nanoparticles in work-intensive periods were found significantly higher (up to 773000 particles/cm3), compared to the non-working periods (147000 particles/cm3) and work-less intensive periods (365000 particles/cm3).. The highest mass concentration value ranged from 8 to 23 mg/m3. X-ray dispersive analysis confirmed the presence of carbon, potassium, oxygen, iron, aluminium, zinc, silicon and phosphorus as integral elements of dental restorative materials in form of nanoparticle clusters, all smaller than 100 nm. We concluded that dental employees are exposed to...
COBISS.SI-ID: 33661657
We report on a new approach to increase the fracture resistance of endodontically treated teeth. We propose a preparation of horizontal internal plateau (IP) in dentine and the use of retentive zirconia posts to achieve a more favourable load transmission. The aim of our work was to investigate the effect of the IP depth and the post diameter on the fracture resistance and the failure mode of maxillary central incisors. Seventy-two teeth were, divided into six groups of 12. IP 4 mm in diameter and 0, 1 or 2 mm in depth was prepared and zirconia posts of two diameters luted. Specimens were loaded until failure and fractures were classified as reparable or not. Two-way ANOVA, Tukey%s HSD test and Poisson regression were used for statistical analysis (% = 0.05). Significantly improved fracture resistance and predominantly favourable failure modes were found when 2-mm deep IP is prepared.
COBISS.SI-ID: 31645735
Samples of Nitinol were oxidized using different procedures in order to improve their biocompatibility and prevent the release of Ni. The evolution of the surface oxide films was monitored using Auger electron spec-troscopy (AES). The only procedure that led to the formation of nickel-free oxide films involved a pre-treatment with hydrogen plasma for 10 s followed by a treatment with a plasma composed of 90% H2 and 10% O2. Optical emission spectroscopy revealed an extremely high dissociation fraction for both the hydrogen and oxygen molecules at a discharge power of 600 W, where the luminous plasma was concentrated in a volume of about0.1 dm3. The extreme chemical reactivity of such a plasma resulted in the formation of an oxide film in about 15 s, meaning that external oxidation took place. The biocompatibility investigations, performed according to the ISO standard protocol using L929 cells, showed the absence of any cytotoxic effects that might be due to a contact between the biological materials and nickel. The investigation of nickel release of samples exposed to Hank’s solution, measured by ICP-OES showed negligible Ni concentration.
COBISS.SI-ID: 21981974
Background/Objectives: Since a high prevalence of back anomalies has been reported among subjects with crossbite, the aim was to assess the degree of back symmetry among subjects with (crossbite) and without (control) unilateral functional crossbite during the pre-pubertal growth phase. Methods: A group of 70 subjects (36 boys, 34 girls; 6.8 +- 1.2 years) in the primary or mixed dentition phase were included. Clinical assessment of head posture, shoulder, scapula and hip height were performed with the subject standing, and differences between the left and right side greater than 5 mm recorded. Asymmetry of the scapula and trunk prominence greater than 8 mm was recorded along with the prominence of thoracic and lumbar paravertebral musculature during the forward- bending test. Back symmetry was assessed qualitatively and quantitatively on colour deviation maps of superimposed mirrored three-dimensional back scans at a tolerance level of 2 mm. Results: No significant differences were observed between the groups regarding the frequency of clinically assessed back anomalies. The percentage of back symmetry was slightly lower in the crossbite than that in the control group (71.4 +- 13.3% and 79.2 +- 12.1%, respectively). A significant association ( P ( 0.05) was seen between scapula plane inclination (OR = 3.41) and scapula prominence inequalities (OR = 3.29) and unilateral functional crossbite, while hip height inequalities (OR = 0.94) were more frequent in the control group....
COBISS.SI-ID: 33949657